/* png.c - load PNG image from file
 *
 * Raster graphics library
 *
 * Copyright (c) 1997-2003 Alfredo K. Kojima
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Library General Public License for more details.
 *
 *  You should have received a copy of the GNU Library General Public
 *  License along with this library; if not, write to the Free
 *  Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
 *  MA 02110-1301, USA.
 */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

#include <png.h>

#include "wraster.h"
#include "imgformat.h"

RImage *RLoadPNG(RContext *context, const char *file)
{
  char *tmp;
  RImage *image = NULL;
  FILE *f;
  png_structp png;
  png_infop pinfo, einfo;
  png_color_16p bkcolor;
  int alpha;
  int x, y, i;
  double gamma, sgamma;
  png_uint_32 width, height;
  int depth, junk, color_type;
  png_bytep *png_rows;
  unsigned char *ptr;

  f = fopen(file, "rb");
  if (!f) {
    RErrorCode = RERR_OPEN;
    return NULL;
  }
  png =
      png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, (png_error_ptr)NULL, (png_error_ptr)NULL);
  if (!png) {
    RErrorCode = RERR_NOMEMORY;
    fclose(f);
    return NULL;
  }

  pinfo = png_create_info_struct(png);
  if (!pinfo) {
    RErrorCode = RERR_NOMEMORY;
    fclose(f);
    png_destroy_read_struct(&png, NULL, NULL);
    return NULL;
  }

  einfo = png_create_info_struct(png);
  if (!einfo) {
    RErrorCode = RERR_NOMEMORY;
    fclose(f);
    png_destroy_read_struct(&png, &pinfo, NULL);
    return NULL;
  }

  RErrorCode = RERR_INTERNAL;
#if PNG_LIBPNG_VER - 0 < 10400
  if (setjmp(png->jmpbuf)) {
#else
  if (setjmp(png_jmpbuf(png))) {
#endif
    fclose(f);
    png_destroy_read_struct(&png, &pinfo, &einfo);
    if (image)
      RReleaseImage(image);
    return NULL;
  }

  png_init_io(png, f);

  png_read_info(png, pinfo);

  png_get_IHDR(png, pinfo, &width, &height, &depth, &color_type, &junk, &junk, &junk);

  /* sanity check */
  if (width < 1 || height < 1) {
    fclose(f);
    png_destroy_read_struct(&png, &pinfo, &einfo);
    RErrorCode = RERR_BADIMAGEFILE;
    return NULL;
  }

  /* check for an alpha channel */
  if (png_get_valid(png, pinfo, PNG_INFO_tRNS))
    alpha = True;
  else
    alpha = (color_type & PNG_COLOR_MASK_ALPHA);

  /* allocate RImage */
  image = RCreateImage(width, height, alpha);
  if (!image) {
    fclose(f);
    png_destroy_read_struct(&png, &pinfo, &einfo);
    return NULL;
  }

  /* normalize to 8bpp with alpha channel */
  if (color_type == PNG_COLOR_TYPE_PALETTE && depth <= 8)
    png_set_expand(png);

  if (color_type == PNG_COLOR_TYPE_GRAY && depth <= 8)
    png_set_expand(png);

  if (png_get_valid(png, pinfo, PNG_INFO_tRNS))
    png_set_expand(png);

  if (depth == 16)
    png_set_strip_16(png);

  if (color_type == PNG_COLOR_TYPE_GRAY || color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
    png_set_gray_to_rgb(png);

  /* set gamma correction */
  if ((context->attribs->flags & RC_GammaCorrection) && context->depth != 8) {
    sgamma = (context->attribs->rgamma + context->attribs->ggamma + context->attribs->bgamma) / 3;
  } else if ((tmp = getenv("DISPLAY_GAMMA")) != NULL) {
    sgamma = atof(tmp);
    if (sgamma < 1.0E-3)
      sgamma = 1;
  } else {
    /* blah */
    sgamma = 2.2;
  }

  if (png_get_gAMA(png, pinfo, &gamma))
    png_set_gamma(png, sgamma, gamma);
  else
    png_set_gamma(png, sgamma, 0.45);

  /* do not remove, required for png_read_update_info */
  png_set_interlace_handling(png);

  /* do the transforms */
  png_read_update_info(png, pinfo);

  /* set background color */
  if (png_get_bKGD(png, pinfo, &bkcolor)) {
    image->background.red = bkcolor->red >> 8;
    image->background.green = bkcolor->green >> 8;
    image->background.blue = bkcolor->blue >> 8;
  }

  png_rows = calloc(height, sizeof(png_bytep));
  if (!png_rows) {
    RErrorCode = RERR_NOMEMORY;
    fclose(f);
    RReleaseImage(image);
    png_destroy_read_struct(&png, &pinfo, &einfo);
    return NULL;
  }
  for (y = 0; y < height; y++) {
    png_rows[y] = malloc(png_get_rowbytes(png, pinfo));
    if (!png_rows[y]) {
      RErrorCode = RERR_NOMEMORY;
      fclose(f);
      RReleaseImage(image);
      png_destroy_read_struct(&png, &pinfo, &einfo);
      while (y-- > 0)
        if (png_rows[y])
          free(png_rows[y]);
      free(png_rows);
      return NULL;
    }
  }
  /* read data */
  png_read_image(png, png_rows);

  png_read_end(png, einfo);

  png_destroy_read_struct(&png, &pinfo, &einfo);

  fclose(f);

  ptr = image->data;

  /* convert to RImage */
  if (alpha) {
    for (y = 0; y < height; y++) {
      for (x = 0, i = width * 4; x < i; x++, ptr++) {
        *ptr = *(png_rows[y] + x);
      }
    }
  } else {
    for (y = 0; y < height; y++) {
      for (x = 0, i = width * 3; x < i; x++, ptr++) {
        *ptr = *(png_rows[y] + x);
      }
    }
  }
  for (y = 0; y < height; y++)
    if (png_rows[y])
      free(png_rows[y]);
  free(png_rows);
  return image;
}
